The Prophet ﷺ said, "When one of you is invited to a meal, let him accept the invitation," or he said, "let him come to it."Ibn Umar used to accept invitations whether he was fasting or not.
حدثنا عفان حدثنا وهيب حدثنا أيوب عن نافع
عن النبي ﷺ قال إذا دعي أحدكم إلى الدعوة فليجب أو قال فليأتها قال وكان ابن عمر يجيب صائما ومفطرا
No references are available.
Its isnad is sahih, and it is a longer version of 5367, see also 5703.